diff --git a/lib/core/streams/aes-crypto-stream.js b/lib/core/streams/aes-crypto-stream.js
index 530a0b85..78eed6e8 100644
--- a/lib/core/streams/aes-crypto-stream.js
+++ b/lib/core/streams/aes-crypto-stream.js
@@ -29,7 +29,7 @@
 /* global crypto, TransformStream */
 // deno-lint-ignore-file no-this-alias
 
-import { UNDEFINED_VALUE } from "../constants.js";
+import { UNDEFINED_VALUE, UNDEFINED_TYPE, FUNCTION_TYPE } from "../constants.js";
 import { encodeText } from "./../util/encode-text.js";
 import {
 	cipher,
@@ -56,8 +56,6 @@ const SALT_LENGTH = [8, 12, 16];
 const KEY_LENGTH = [16, 24, 32];
 const SIGNATURE_LENGTH = 10;
 const COUNTER_DEFAULT_VALUE = [0, 0, 0, 0];
-const UNDEFINED_TYPE = "undefined";
-const FUNCTION_TYPE = "function";
 // deno-lint-ignore valid-typeof
 const CRYPTO_API_SUPPORTED = typeof crypto != UNDEFINED_TYPE;
 const subtle = CRYPTO_API_SUPPORTED && crypto.subtle;
diff --git a/lib/core/streams/common-crypto.js b/lib/core/streams/common-crypto.js
index 27a4d8f1..6fa6730b 100644
--- a/lib/core/streams/common-crypto.js
+++ b/lib/core/streams/common-crypto.js
@@ -28,11 +28,12 @@
 
 /* global crypto */
 
+import { FUNCTION_TYPE, UNDEFINED_TYPE } from "../constants.js";
 import {
 	random
 } from "./codecs/sjcl.js";
 
-const GET_RANDOM_VALUES_SUPPORTED = typeof crypto != "undefined" && typeof crypto.getRandomValues == "function";
+const GET_RANDOM_VALUES_SUPPORTED = typeof crypto != UNDEFINED_TYPE && typeof crypto.getRandomValues == FUNCTION_TYPE;
 
 const ERR_INVALID_PASSWORD = "Invalid password";
 const ERR_INVALID_SIGNATURE = "Invalid signature";
diff --git a/lib/core/util/stream-codec-shim.js b/lib/core/util/stream-codec-shim.js
index 2e63be99..e505b0a3 100644
--- a/lib/core/util/stream-codec-shim.js
+++ b/lib/core/util/stream-codec-shim.js
@@ -29,6 +29,8 @@
 
 // deno-lint-ignore-file no-this-alias
 
+import { FUNCTION_TYPE, UNDEFINED_VALUE } from "../constants.js";
+
 export {
 	initShimAsyncCodec
 };
@@ -42,7 +44,7 @@ function initShimAsyncCodec(library, options = {}, registerDataHandler) {
 
 function objectHasOwn(object, propertyName) {
 	// eslint-disable-next-line no-prototype-builtins
-	return typeof Object.hasOwn === "function" ? Object.hasOwn(object, propertyName) : object.hasOwnProperty(propertyName);
+	return typeof Object.hasOwn === FUNCTION_TYPE ? Object.hasOwn(object, propertyName) : object.hasOwnProperty(propertyName);
 }
 
 function createCodecClass(constructor, constructorOptions, registerDataHandler) {
@@ -61,7 +63,7 @@ function createCodecClass(constructor, constructorOptions, registerDataHandler)
 					codecAdapter.pendingData = new Uint8Array(data);
 				}
 			};
-			if (objectHasOwn(options, "level") && options.level === undefined) {
+			if (objectHasOwn(options, "level") && options.level === UNDEFINED_VALUE) {
 				delete options.level;
 			}
 			codecAdapter.codec = new constructor(Object.assign({}, constructorOptions, options));
diff --git a/lib/core/zip-fs-core.js b/lib/core/zip-fs-core.js
index 1ef53182..98d6fd42 100644
--- a/lib/core/zip-fs-core.js
+++ b/lib/core/zip-fs-core.js
@@ -52,6 +52,7 @@ import {
 import {
 	Entry
 } from "./zip-entry.js";
+import { UNDEFINED_VALUE } from "./constants.js";
 
 class ZipEntry {
 
@@ -433,7 +434,7 @@ class ZipDirectoryEntry extends ZipEntry {
 
 	async exportZip(writer, options) {
 		const zipEntry = this;
-		if (options.bufferedWrite === undefined) {
+		if (options.bufferedWrite === UNDEFINED_VALUE) {
 			options.bufferedWrite = true;
 		}
 		await Promise.all([initReaders(zipEntry, options.readerOptions), initStream(writer)]);
diff --git a/lib/core/zip-reader.js b/lib/core/zip-reader.js
index 203cebf9..8d76bcbb 100644
--- a/lib/core/zip-reader.js
+++ b/lib/core/zip-reader.js
@@ -455,7 +455,7 @@ class ZipEntry {
 				await writable.getWriter().close();
 			}
 		}
-		return checkPasswordOnly ? undefined : writer.getData ? writer.getData() : writable;
+		return checkPasswordOnly ? UNDEFINED_VALUE : writer.getData ? writer.getData() : writable;
 	}
 }
 
diff --git a/lib/z-worker-bootstrap-fflate.js b/lib/z-worker-bootstrap-fflate.js
index 35641bec..592401fe 100644
--- a/lib/z-worker-bootstrap-fflate.js
+++ b/lib/z-worker-bootstrap-fflate.js
@@ -31,9 +31,10 @@
 
 import "./core/z-worker-core.js";
 import { initShimAsyncCodec } from "./core/util/stream-codec-shim.js";
+import { UNDEFINED_VALUE } from "./core/constants.js";
 
 self.initCodec = () => {
-	const { Deflate, Inflate } = initShimAsyncCodec(fflate, undefined, (codec, onData) => codec.ondata = onData);
+	const { Deflate, Inflate } = initShimAsyncCodec(fflate, UNDEFINED_VALUE, (codec, onData) => codec.ondata = onData);
 	self.Deflate = Deflate;
 	self.Inflate = Inflate;
 };
\ No newline at end of file
diff --git a/lib/zip-fflate-shim.js b/lib/zip-fflate-shim.js
index 07e63b8d..efe8b735 100644
--- a/lib/zip-fflate-shim.js
+++ b/lib/zip-fflate-shim.js
@@ -31,5 +31,7 @@ import {
 	Inflate as FflateInflate
 } from "fflate";
 import { initShimAsyncCodec } from "./core/util/stream-codec-shim.js";
-const { Deflate, Inflate } = initShimAsyncCodec({ Deflate: FflateDeflate, Inflate: FflateInflate }, undefined, (codec, onData) => codec.ondata = onData);
+import { UNDEFINED_VALUE } from "./core/constants.js";
+
+const { Deflate, Inflate } = initShimAsyncCodec({ Deflate: FflateDeflate, Inflate: FflateInflate }, UNDEFINED_VALUE, (codec, onData) => codec.ondata = onData);
 export { Deflate, Inflate };
\ No newline at end of file